Basket-style carriers are commonly employed to package beverage bottles. A conventional arrangement includes a separate cell for each bottle and a center handle partition. Normally, the carriers are fabricated from a blank which is folded and glued into collapsed carrier form, after which the collapsed carrier is erected. In one design the bottom panel is integrally formed so that when the collapsed carrier is erected bottles may be inserted down onto the bottom panel through the open cells. In another design the bottom panel is formed by connecting the bottom panel forming flaps after the bottles have been inserted into the cells. The bottles are commonly inserted in this latter design by moving an opened carrier down over a group of stationary bottles, although the bottles may also be inserted by moving them down into the opened carrier.
In either case, the carrier must be squared prior to forming the bottom panel, and the subsequently formed bottom panel must be maintained in squared condition. This can be a difficult task inasmuch as the loading of an opened carrier can leave the bottom panel forming flaps in a position which, if maintained, will result in an out-of-square bottom. Even though an out-of-square bottom can be made structurally sound, the carrier does not present as attractive an appearance as a carrier which has been first squared up and the various carrier elements connected so as to maintain the squared condition.
Attempts have been made to provide bottom panel structures which overcome these problems. For example, U.S. Pat. No. 4,989,799 discloses basket-style carriers incorporating center keel tabs which extend through slots in the bottom panel flaps and are then folded back into the interior of the carrier through another slot in the outer bottom panel flap. This arrangement is intended to provide a square bottom panel by maintaining both bottom panel flaps in the desired relationship with each other and with the center handle panel. However, it requires the bottom panel flaps to be precisely aligned in order to receive the keel tabs. In addition, the tab folding operation requires relatively complicated machinery which can also slow the speed of the packaging line.
Another problem with basket-style carriers is the lack of rigidity encountered in a typical design in which the center handle panel is connected only to the end panels and is spaced from the bottom panel. Attempts have been made to strengthen such a structure by providing center keel tabs which are adhered to the bottom panel. Examples of such a design are found in U.S. Pat. Nos. 4,915,218 and 4,919,261 which disclose keel tabs that are folded and glued to the inner face of one of the bottom panel forming flaps. Such an arrangement does not assist in squaring the bottom panel, but only strengthens it after the bottom panel has been formed.
It would be highly desirable to be able to square the bottom panel of a basket-style carrier in a simple but reliable manner, while at the same time strengthening the bottom panel.